Hitherto, coating of outer peripheral surface of a pillar structure of which the outer peripheral surface is curved surface, such as cylindrical columnar body or elliptic columnar body, has usually been carried out by hand labor, which is not efficient. Thus, the inventors proposed an apparatus for coating the outer peripheral surface of a ceramic honeycomb structure (a pillar structure) (JP-A-4-64768). According to this apparatus, the outer peripheral surface of a ceramic honeycomb structure of which the outer peripheral portions have been previously removed by working is coated with a slurry to form an outer wall part, and thus a product having a sufficient strength can be obtained even from such a honeycomb fired body as having deformed cells on the peripheral part (outer peripheral surface). However, in the case of this apparatus for coating the outer peripheral surface, there are caused omission of coating at both end portions of the outer peripheral surface, difficulty in removal of the product after coating and contamination of the apparatus with coating materials, resulting in problems in both the quality and the operability.
Furthermore, the inventors proposed an apparatus for coating the outer peripheral surface of a columnar body (pillar structure) (JP-A-8-323727). This apparatus is characterized by being provided with a first pallet holding the columnar body, a mechanism rotating on the central axis of the first pallet and a smoothing plate provided with a given clearance from the outer periphery of the columnar body. According to this apparatus, a coating material is supplied from a nozzle (supplying and coating means) and coated on a rotating columnar body disposed on the first pallet and is smoothed by the smoothing plate, and thus a coated columnar body high in dimensional accuracy can be obtained in a short time as compared with hand-coating. However, this outer peripheral surface coating apparatus suffers from the problems that since the direction of the central axis of the pillar structure is nearly vertical direction and the nozzle is disposed along the whole outer peripheral surface between the both ends (through the whole outer peripheral surface between the upper side and the lower side), the coating material scraped by the smoothing plate flows down (to the lower side of the outer peripheral surface) and stays at the lower part of the nozzle, which deposits on the outer peripheral surface to cause thick coating on the lower part of the outer peripheral surface. Therefore, there is a problem that the coating portion on the lower part of the outer peripheral surface on which the coating becomes too thick is cracked during drying after coating.